The invention relates to a partially percussive power tool having a flushing head such as a drilling or chisel hammer preferably deployed in mining operations.
High-performance drilling or chisel hammers with a mass of greater than 10 kg, such as those used in mining operations for drilling blast holes, have a flushing bore at least in part running axially along a long tool shaft for passage of liquid flushing and cooling means such as water, which is introduced either centrally via the tool holder or via a flushing head that embraces the tool shank in a zone of a flushing opening.
According to DE 10127984, a rotary and percussive power tool used in mining operations for drilling blastholes has a flushing head that is integral with the housing and radially arranged within a hollow-cylindrical tool holder integrated with the power tool while being impact-freely rotationally driving and guiding for the insertion end of a rock drill. Its long tool shank has an axially running flushing bore hole having front end rotation drive grooves facing in the direction of the insertion end and is closed at the machine end for passage of a liquid flushing and cooling agent such as water, which reaches a transverse bore in the tool shank through the tool holder via a flushing head integrated on the power tool. The machine-side relative to the transverse bore hole required sealing of the insertion end relative to the machine-side open tool holder is dependent on the surface quality of the seal of the insertion end, which is particularly problematic in the rough mining trade and consequently limits the service life of the power tool. In addition, the transverse bore hole represents a predetermined breaking point for the tool shank that is highly stressed with axial striking and this, too, limits the service life of the tool.
In addition, according to DE 3610680, in a percussive power hand tool having a tool holder integrated in the power tool machine for a percussive tool, the tool guide in the integrated tool holder and the rotary and percussive transmission is configured in a pot-shaped anvil head, which is sealed against the pneumatic striking mechanism generating the axial impact.
Furthermore, according to U.S. Pat. No. 4,711,609, the percussive transmission is done by an annular impact face of the percussively driven, hollow cylindrical tool holder on a ring flange on the insertion end of the tool.